Process for dyeing paper with disazo dyestuffs and compositions therefor

ABSTRACT

DIRECT DISAZO AND TETRAAZO UREA DYES USEFUL FOR DYEING CELLULOSIC MATERIALS AND CONSISTING OF SALTS OF N,N&#39;&#39;-BIS(SULFO- AND CARBOXYARYLAZOARYL) UREAS AND SALTS OF N,N&#39;&#39;BIS(SULFO- AND CARBOXYARYLAZOARYLAZARYL) UREAS, ALSO KNOWN AS BIS(ANILINO)KETONES, FOR EXAMPLE, BIS(3-METHYL4-((6.8-DISULFO-2-NAPHTHYLAZO)ANILINO) KETONE, THE CATIONIC PORTIONS OF SAID SALTS BEING AT LEAST 50 ATOMS PERCENT LITHIUM AND/OR AMMONIUM, AND THE REMAINDER, SODIUM AND/OR POTASSIUM, A PROCESS FOR PREPAING SAID DYES, AND STABLE AQUEOUS SOLUTIONS OR SUSPENSION OF SAID DYES.

United States Patent 015cc 3,684,425 Patented Aug. 15, 1972 PROCESS FORDYEING PAPER WITH DISAZO DYESTUFFS AND COMPOSITIONS THEREFOR John M.Ross, Wilmington, Del., and Harvey I. Stryker, Carneys Point, N.J.,assignors to E. I. du Pont de Nemours and Company, Wilmington, Del.

No Drawing. Original application Oct. 3, 1968, Ser. No. 764,936, nowPatent No. 3,621,008. Divided and this application Feb. 1, 1971, Ser.No. 111,616

Int. Cl. D2111 N46 US. C]. 8-7 3 Claims ABSTRACT OF THE DISCLOSUREDirect disazo and tetraazo urea dyes useful for dyeing cellulosicmaterials and consisting of salts of N,N'-bis- (snlfoandcarboxyarylazoaryl) ureas and salts of N,N'- bis(sulfoandcarboxyarylazoarylazoaryl) ureas, also known as bis(anilino)ketones, forexample, bis[3-methyl- 4-[(6.8-disulfo-2-naphthyl)azo]anilino] ketone,the cationic portions of said salts being at least 50 atoms percentlithium and/or ammonium, and the remainder, sodium and/or potassium, aprocess for preparing said dyes, and stable aqueous solutions orsuspensions of said dves.

CROSS-REFERENCE TO RELATED APPLICATIONS This is a division ofapplication Ser. No. 764,936, filed Oct. 3, 1968 now US. Patent No.3,621,008.

BACKGROUND OF THE INVENTION (1) Field of the invention This inventionrelates to direct disazo and tetraazo urea dyes for cellulosicmaterials, and more particularly, to salts of N,N'-bis(sulfoandcarboxyarylazoaryl) ureas and salts of N,N-bis(sulfoandcarboxyarylazoarylazoaryl) ureas.

(2) Description of the prior art N,N'-bis-(sulfoand carboxyarylazoaryl)ureas and certain salts thereof are known as direct disazo dyes forcellulosic materials. A basic phosgenation process of manufacture ofsuch dyes may be found in US. 935,018 which issued Sept. 28, 1909 toGiinther and Hesse. Modifications and improvements in such dyes andtheir preparation are disclosed in U.S. 2,666,757 which issued Jan. 19,1954 to Richter, and in German 1,068,406 which was granted Nov. 5, 1959.

The direct dyes of this type are widely used in the dyeing of paper orpaper pulp and are generally sold in the form of powders. These dyepowders are troublesome to manufacture and use in the mills for dyeingpaper. Drying, grinding, dust-treatment, and standardization operationsare required in the manufacture of the dye powders. In addition todusting problems, it has been found in mill experience that the coldwater beater dyeing strength of the dye powders on paper prepared fromthe dyed pulp is generally low. Moreover, the slow rate at which dyepowders dissolve in cold water is a particular disadvantage, especiallyduring winter months when the temperature of water used in paper beaterdyeing operations may approach the freezing point. This lack ofsolubility, also, makes it diflicult to use such dyes in continuoussystems where pumping and metering of uniform dye solutions orsuspensions is necessary for etficient operation.

The prior art method of preparing the aforesaid dyes involves thephosgenation of amino derivatives of arylazoaryl compounds, with thecoupling by-product hydrogen chloride being neutralized by a base suchas sodium hydroxide or sodium carbonate. Using such bases, a precipitatebegins to form shortly after phosgenation is commenced and theprecipitate contains both product and reactant. Hence, the reactionyields are low and the product often must be purified by a lengthyprocedure before it can be used for dyeing.

OBJECTS AND SUMMARY OF THE INVENTION It is an object of the presentinvention to provide a novel group of direct disazo and tetraazo ureadyes which are salts of N,N'-bis(sulfoand carboxyarylazoaryl) ureas andsalts of N,N'-bis(sulfoand carboxyarylazoarylazoaryl) ureas. Anotherobject is to provide such dyes having water solubilities which are threeto four times those of similar prior art compounds. It is a furtherobject to provide direct dyes of the above type as stable aqueoussolutions or suspensions. An additional object is to provide paper dyeshaving superior performance when used in the cold water beater dyeingsystem. Astill further object is to provide a phosgenation process forthe manufacture of dyes of the above type, said process being muchfaster than prior art phosgenation processes and such that thephosgenation reaction mass containing the dye can be standardized in thereaction vessel and then packaged for shipment and used directly indyeing processes, thus eliminating isolation, purification and treatmentof the dye itself. i

The objects of the invention are achieved by means of a class of dyeshaving the formula A is a phenyl or phenylene group containing 1 to 2substituents selected from CO M and SO M and not in excess of 2substituents selected from OH, OCH and OH,, or a naphthyl or naphthylenegroup containing 1 to 2 substituents selected from COgM and -SO M andnot in excess of 3 substituents selected from OH, OCH, and CH and M is acation selected from Li+, Na+, K+ and NHJ, with at least 50 atom percentselected from Li+ and NH B is a phenylene group containing not in excessof 2 substituents selected from OH, -OCH;,, and CH andxis1to2,yis0to1,andthesurnofxandyis1to2;

said dyes being produced by phosgenating an appropriate azo amine,produced by conventional means and contain ing not in excess of about 20weight percent, based on dry weight, of a chloride or sulfate salt ofsodium or potassium, said phosgenation being carried out in an aqueousmedium while maintaining a pH of 4.0-7.0 with a base selected fromammonium hydroxide, lithium hydroxide, lithium bicarbonate and lithiumcarbonate.

DESCRIPTION OF THE INVENTION The present invention resides in thediscovery of a class of dyes which are salts of N,N-bis(sulfoandcarboxyarylazoaryl) ureas and salts of N,N-bis(sulfoandcarboxyarylazoarylazoaryl) ureas, said dyes having improved properties,especially greater purity as prepared and improved Water solubility,over similar prior art dyes. The present invention also resides in thediscovery of a phosgenation process for the preparation of the aforesaiddyes, the process being such that the reaction can be carried outquicker and at higher yields than similar prior art phosgenationprocesses. Finally, the present invention resides in the discovery thatthe liquid phosgenation reaction mixture resulting from operation of theprocess of this invention and containing the novel dyes of thisinvention can be used directly for dyeing cellulosics, thus eliminatingthe steps of isolation, purification and after- 3 treatment required inthe preparation and use of similar prior art dyes.

More particularly, one aspect of the present invention resides in thediscovery of a novel class of salts of N,N'-bis(sulfoandcarboxyarylazoaryl) ureas and salts of N,N'-bis(sulfoandcarboxyarylazoarylazoaryl) ureas having the formula wherein: a

A is a phenyl or phenylene group containing 1 to 2 substituents selectedfrom CO M and SO M and not in excess of 2 substituents selected from OH,--0CH and --CH or a naphthyl or naphthylene group containing 1 to 2substituents selected from -CO M and SO M and not in excess of 3substituents selected from ---OH, OCH, and -CH and M is a cationselected from Li+, Na K+ and NHJ, with at least 50 atom percent selectedfrom Li+ and NHJ;

B is a phenylene group containing not in excess of 2 substituentsselected from 0H, -OCH;, and CH and xis1to2,yis0tol,andthesumofxandyis1to2.

The aforesaid dyes are prepared by phosgenating an appropriate azoamine. Azo amines can be prepared by well-known prior art methods, forexample, by diazotizing an appropriate sulfoand/ or carboxyaryl amine,and then coupling the diazonium to a second appropriate aryl amine, thatis, an aniline. Such azo amines, after phosgenati-on, often yield disazoureas which are yellow. If it is desired to prepare a tetrazo dye ofthis invention (may yield other color shades), the initial diazonium canbe coupled to a second sulfoand/ or carboxyaryl amine, and the resultantazo amine can be diazotized and coupled to the aniline. Alternatively,the sulfoand/or carboxyaryl amine can be diazotized, coupled to theaniline, and the resultant azo amine can be diazotized and coupled to asecond aniline. The aforesaid sulfoand/ or carboxyaryl amines usuallyare prepared by prior art methods as the sodium or potassium salts andmay contain sodium or potassium chloride or sulfate. The onlyprerequisite for use of said amines in the present invention is that theamount of salt must not exceed about 20 weight percent, based on dryweight. Removal of excess salt may be effected by washing the amine witha dilute aqueous salt brine, for example, 3 weight percent aqueoussodium chloride. Preferably, the brine is acidified, for example, to apH of about 3 with hydrochloric acid, to convert the amine at leastpartly to the free sulfo and/ or carboxy acid, thus further reducing theamount of sodium and/ or potassium ions.

The phosgenation reaction of this invention is carried out byintroducing phosgene into an aqueous solution of the aforesaid azoamine. A critical feature of the invention is that sufficient lithiumand/or ammonium ions must be present during the phosgenation to maintaineither a solution or a finely-divided fluid slurry. To ensure thepresence of suflicient lithium and/or ammonium ions at the start of thephosgenation, the aqueous solution of azo amine may be rendered stronglyalkaline, for example, to a pH of -11, using a base selected fromammonium hydroxide, lithium hydroxide, lithium bicarbonate and lithiumcarbonate prior to introduction of any phosgene. As soon as phosgene isadded, for example, by bubbling it into the reaction vessel beneath thesurface of the aqueous solution, the pH decreases due to liberation ofhydrogen chloride. During the reaction, except for the momentary initialstage if the solution has been made alkaline as described above, the pHof the reaction mixture is maintained at 4.07.0 With one of theaforesaid bases. The preferred pH is 6.5-7.0. At a pH less than 4.0 thereaction rate is undesirably slow and it becomes more difiicult tomaintain a solution or fine suspension of reactants and product. At a pHabove 7.0 the com- .4 peting hydrolysis of phosgene is favored, thusresulting in excessive loss of this reactant. The preferred base islithium hydroxide. Lithium carbonate is more difiicult to add since itslow water solubility precludes use of concentrated aqueous solutions.Lithium bicarbonate is less basic and, therefore, is more costly toemploy. Ammonium hydroxide provides the advantages of the process ofthis invention but somewhat deleteriously affects the strength of thedyes produced when used to dye cellulosics.

The reaction temperature should be such that either a solution or a veryfluid finely-divided slurry is maintained through the reaction. Thetemperature selected will depend, to a certain extent, on the volume ofwater present, and the latter will depend, to a certain extent, on thedye concentration desired in the reaction product since the presentinvention makes possible the direct use of the liquid reaction product.The preferred temperature is 7G- 7 5 C. since at this temperature anexcellent combination of reaction rate and solubility can be achieved.Moreover, at this temperature the reaction can be carried out atatmospheric pressure, thus simplifying equipment requirements.

Theoretically, two moles of appropriate azo amine are required for eachmole of phosgene. Since hydrolysis of phosgene is unavoidable, an excessof the stoichiometric amount of this reactant must be employed, althoughit has been discovered that the loss of phos'gene through bydrolysis ismuch less in the instant process than in prior art phosgenationprocesses. correspondingly, the amount of salt by-product is less in thepresent invention. Moreover, the reaction rate of the principal reactionin the present invention is appreciably higher than in prior artphosgenations. Two-fold increases in reaction rate (three times as fast)have been observed. Since it is diflicult to predict the amount ofphosgene which will be lost via hydrolysis, it is preferred to determinethe completion of the reaction by removing, from time to time, a sampleof the reaction mixture and then analyzing said sample for free amine.This may be done, for example, by submitting the sample to adiazotization procedure, and thereafter attempting to couple thediazotization mixture to a dyeproducing compound, for example, ChicagoAcid. With this coupler a blue color Will be produced if the originalsample still contained free azo amine.

When the phosgenation reaction is completed, the reaction mixture iscooled and the pH is adjusted, usually to 7.0-8.0. The liquid reactionproduct then may be sampled for standardization, diluted with water orconcentrated, if necessary, to achieve the desired dye strength, andpackaged for direct sale and use. The process of the present inventiondoes not preclude isolation of the dye product and the use of theresultant dye powder in a manner analogous to similar prior art dyes.All of the advantages of the present invention relative to improvedpreparation, higher solubility of the dyes, and the like, accrue to dyepowders prepared by means of this invention. However, since the presentprocess provides a liquid product usually having about 50 percent of thedye strength of prior art dry powders, economics often favors the use ofthe liquid products directly. By the process of the present inventionstable aqueous solutions or suspensions containing about 10 to about 40weight percent active dye ingredient can be prepared. Moreover, theprocess of the present invention permits the introduction of additives,for example, dispersing agents, directly to the phosgenation reactionmixture. A particularly useful aqueous dye product prepared by theprocess described above contains, on a weight basis,

10-25% dye (as the free acid) 2-5% Cland/or SO up to 3% Na+ and/or K+ upto 8% dispersing agent balance (about 57-87%), to make water.

As indicated above, the phosgenation is carried out with an azo amineprepared from an appropriate sulfoand/ or carboxyaryl amine and anappropriate aniline by wellknown diazotization and coupling techniques.

Also as indicated above, the phosgenation is carried out in the presenceof lithium and/or ammonium ions. The dye products are salts wherein thecation is comprised of at least 50 atom percent lithium and/or ammoniumions, the balance if necessary, being sodium and/or potassium ions.

The process of this invention requires that one of the amines from whichthe azo amine is derived must contain one or two carboxy and/or sulfogroups, or salts thereof. If the amine is a naphthyl amine, it ispreferred that two such acid groups be present, and preferably, twosulfo groups. It is obvious from the above that the present inventioncontemplates the use of sodium and/or potassium salts of sulfoandcarboxyaryl amines as starting materials for the preparation of the azoamines which are subsequently used in the phosgenation process of thisinvention. Other substituents selected from OH, OCH and CH may beattached to the aromatic ring along with the one or two carboxy and/orsulfo groups, or salts thereof. If the amine in question is a naphthylamine, up to three of such other substituents may be present. If theamine in question is a phenyl amine, up to two of such othersubstituents may be present.

The second amine or coupler from which the aforesaid azo amine isderived is a phenyl amine. The simplest such amine is aniline. Othersubstituents may be attached to the aromatic ring in addition to theamino group. Up to two such additional substituents selected from OH,OCH and CH 'may be present.

The preferred dyes of this invention are those represented by theexamples which are presented hereinbelow. Especially preferred are thedyes derived from 2-aminonaphthalene-6,8-disulfonic acid and meta-toluidine, from 2-aminonaphthalene-4,S-disulfonic acid and meta-toluidine,and from 2-aminonaphthalene-4,8-disu1- fonic acid and cresidine(2-amino-4-methylanisole). For the especially preferred dyes, A in thegeneral formula previously shown is either while B is either OH; OCH;

The dyes of the present invention may be used directly in the form of asolution or suspension as prepared, or as dry powders, to dye cellulosicmaterials, especially paper, in the usual paper mill equipment. Thefollowing description represents a typical dyeing operation. Normally0.1 to 3.0 parts of the dye liquid are added to an aqueous slurry of 100parts (dry basis) of bleached sulfite pulp in 5000 parts of water atambient temperature (2 Q 38" C.); 0.5 to 3 parts of rosin size (sodiumrosinate) and 1 to 4 parts of aluminum sulfate octadecahydrate are thenadded. The mixture is thoroughly agitated for 10 to 20 minutes and wateris added as needed to give a total of 20,000 to 25,00 parts. Paper sheetis then made up in the usual manner. The dye liquids of the inventioncan also be used for continuous coloring of paper by constant meteringof the dye liquid into the pulp slurry. A number of advantages accruefrom this procedure, notably rapid and efiicient shade control andquicker changeover from one shade to another because only a small partof the system is normally contaminated with color or colored pulp. Theproblems of dust, and the dissolving of the powdered dye are eliminated.

It already has been noted that the temperature of water used inpapermaking may be close to freezing. The liquid dyes of the inventionshow advantages over prior art dyes under these cold water conditions inthe speed of dissolving and completness of utilization. This is probablydue to the increased solubility of the lithium dye salts, and/or thefinely-divided form of the dye particles in suspension. Although notalways true solutions the product dye liquids can nevertheless be pumpedand metered as liquids of constant composition. The unusual propertiesof the products in conjunction with the unusual process of the inventionhave made it possible to produce stable aqueous dye liquids ofsubstituted urea dyes in relatively high concentrations.

The invention is illustrated in the following examples, which are notintended to be restrictive. All amounts, unless otherwise indicated, areon a weight basis. Lithium hydroxide was employed as the monohydrate.

Example l.-Amino G-acid (2aminonaphthalene-6,8- disulfonic acid(monopotassium salt was diazotized, using hydrochloric acid and sodiumnitrite. Coupling Was accomplished by adding meta-toluidine to the diazomixture at about 25 C. After overnight stirring the temperature wasraised to 35 C. and held for one hour; then the charge was filtered andthe free liquid was blown or sucked out. The material in the filter waswashed with 3% sodium chloride brine whose pH had been adjusted to3.0102 with hydrochloric acid. Residual liquid Was again blown or suckedaway from the cake. This procedure reduced the salt content of thefilter cake in preparation for the phosgenation step.

To a suitable reactor were added 10 parts of water and 9 parts of 20%lithium hydroxide solution. About 20 parts of the2-(4-amino-2'-tolylazo)naphthalene-6,8-disulf0nic monoacid salt from theprevious reaction were then added in the form of filter cake (about 50%water). The charge was heated to 7075 C. and the pH was adjusted to 10.0to 11.0 by adding 20% lithium hydroxide solution. The charge was anoily, amber colored solution at this stage. The volume was adjusted toabout 65 parts by adding water; about 0.5 part of a filter aid(diatomaceous earth) was added and the charge was clarified byfiltration to remove extraneous solids. Phosgene was then added througha leg beneath the surface, the temperature being maintained at 70-75 C.As the phosgene reacted, the pH fell and was maintained at 6.5 to 7.0 byadding 20% lithium hydroxide solution as needed. After about 3 parts ofphosgene had been added, the charge was tested for completion ofreaction by removing a sample and diazotizing it and coupling to ChicagoAcid (a blue color indicates presence of unreacted base). The test wasrepeated thereafter with each additional 0.5 part of phosgene untilreaction was complete. About 4.0 parts of phosgene were required. Whenreaction was complete, 20% lithium hydroxide solution was added to raisethe pH to 7.5 $0.5, and about 0.75 part of dispersing agent (sodium saltof naphthalene-formaldehyde condensateB1ancol) was added and stirred infor about one-half hour. The charge was then cooled to about 25 C. andsampled for standardization. It was diluted with water to give thedesired color strength and finally drummed through an 80 mesh screen(U.S. Burea of Standards, Standard Screen Series, 1919) into shippingcontainers. Active ingredient content was about 20% and the productcontained about 1.0% lithium as Li+ ion and combined lithium (attachedto dye).

The slurry dyed paper and cotton to a reddish-yellow color usingconventional dyeing techniques. It was stable and did not showappreciable settling over a period of several months, although a smallamount of clear liquid was observed at the top of a sample after thatperiod of time.

Example 2.-Wet presscake equivalent to 151.5 parts of Amino G-acid wasdiazotized using hydrochloric acid and sodium nitrite and the diazoslurry was treated with a solution of 93 parts of cresidinehydrochloride dissolved in 350 parts of water. The pH of the couplingmass was raised to 2.5 by the addition of 30% sodium formate and thetemperature was maintained at 35 to 40 C. for 4 hours to complete thereaction. The charge was filtered and the cake was washed with 1000parts of 1% aqueous hydrochloric acid.

The wet cake of the aminoazo base was warmed with 148 parts of 20%lithium hydroxide solution and adjusted so as to give a clear solutionequivalent to 210 parts of pure base in a volume of 850 parts. Thesolution -was warmed to 75 C. and phosgenated as described in Example 1using 20% lithium hydroxide solution as the acid acceptor so as to holdthe pH at 6.5 to 7.0. When the phosgenation reaction was complete, thepH was adjusted to 8.5 with lithium hydroxide and the hot solutions wascooled with agitation in the presence of 17.4 parts of Blancol. Thethick, cold reaction liquid was diluted with water to an activeingredient of 14.4% which gave bright orange tissue dyeings byconventional dyeing procedures.

Example 3.Wet presscake of the monopotassium salt of Amino G-acidequivalent to ll.5 parts of the pure disulfonic acid was dissolved in280 parts of ice and water with the addition of 50 parts of 30% causticsoda. The solution was treated with 125 parts of 34.5% solution ofsodium nitrite and run into an agitated mixture of 380 parts of ice andwater containing 36 parts of concentrated hydrochloric acid. Theresultant slurry was agitated for 1 hour at 25-* -2 C. The reaction masswas filtered and the wet diazo cake (240- parts) was suspended in 250parts of water.

A solution of 93 parts of cresidine hydrochloride in 350 parts of waterwas added to the diazo slurry, the coupling mass was warmed to 35 C.,and the pH was raised to 3.5 by the addition of the necessary amount ofa 20% solution of lithium hydroxide. When the reaction was complete, asindicated by the total disappearance of the diazo compound, the pH ofthe mass was raised further to 7.0 with 20% lithium hydroxide givingaproximately 920 parts of a clear, deep red solution of the salt of2-(4'- amino-5'-methoxy-2'-tolylazo)naphthalene-6,8 disulfonic acid.

The entire coupling solution was warmed to 7 5 C. and phosgenated asdescribed in the previous examples using 20% lithium hydroxide solutionas the acid acceptor to hold the pH in the range of 6.5 to 7.0. Thephosgenation was continued until the aminoazo base was shown to becompletely reacted, giving a clear solution of the substituted urea dye.The hot solution was cooled with agitation and treated with dispersant(-Blancol) and water as diluent to give a stable liquid color having anactive ingredient of 14.6%, at which strength it was used to dye tissuean attractive orange shade.

Example 4.About 200 parts of1-(4'-amino-3'-methoxyphenylazo)-benzene-3-sulfonic acid filter cake(prepared from sodium metanilate and ortho-anisidine omega sulfonic acidby prior art procedure) were slurried in 300 parts of water and warmedto 7075 C. The resultant slurry was treated with 100 parts of 20%lithium hydroxide monohydrate solution to form a clear solution having apH of 8.1 at 75 C. The hot solution was diluted to 850 parts by volume.Titration of an aliquot sample with standard titanium trichloridesolution indicated that 66.5 parts of actual organic base were present.The solution was transferred to a glass flask equipped with an efiicientagitator and gas distributor. The apparatus was set up in a ventilatedhood and also equipped with an exhaust gas scrubber system adequate forremoval of toxic exhaust gases. A stream of phosgene was fed under thesurface of the hot agitated solution, the temperature being maintainedat 7075 C. The pH was allowed to fall to 6.5 to 7.0 and was thereaftermaintained in that range by the continuous addition of lithium hydroxidesolution made up in the proportion of 20 parts lithium hydroxidemonohydrate to parts of water. Course of the phosgenation reaction wasfollowed by periodic removal of small aliquot samples which wereanalyzed to determine the disappearance of the amine-containing base.When the reaction was complete, as indicated by complete disappearanceof base, 35 parts of phosgene had been fed to the reactor. The solutionwas still clear. The mass was treated with 10 parts of dispersing agent(Blancol) and transferred to a larger flask for standardization. It wasthere cooled to 20 C. during which time part of the phosgenated productprecipitated, resulting in a thin mobile slurry totalling 1190 parts.The mass was standardized to the desired strength by dye test comparisonand subsequent addition of the required amount of water. The liquid wasused to dye paper and cotton a greenish-yellow color.

Example 5.The phosgenation procedure of Example 4 was repeated using amixture of 63.8 parts of 1-(4'- amino-3'-methoxyphenylazo)benzene 3sulfonic acid and 11.3 parts of 1- (4'-amino 3' -methoxy-6'-tolylazo)benzene-S-sulfonic acid. Both intermediates were prepared by prior artprocedure. A solution of these compounds as their lithium salts at atotal volume of 1000 parts was used. A clear solution was maintaniedthroughout the phosgenation performed at 70-75" C. while the pH wasmaintained at 6.5 to 7.0 by addition of 20% lithium hydroxide solution.At the completion of the phos-genation reaction the entire mass wasconverted to powder by spray drying and the crude mass was standardizedto suitable strength. The dye produced in this way showed excellentsolubility and dyed paper by tissue or regular beater methods agreenish-yellow, although noticeably redder than paper dyed by theproduct obtained in Example 4.

Example 6.The phosgenation procedure of Example 4 was repeated using amixture of 49.8 parts of 1-(4'-amino-3'-methoxyphenylazo)benzene-B-sulfonic acid, 37.2 parts of 5-(4'-aminophenylazo) 2 hydroxybenzoic acid, and 11.4 parts of 5-(4-aminophenylazo) 2 hydroxy-3- methylbenzoic acid as the lithium salts,adjusted with water to a total volume of 850 parts. All intermediateswere prepared by prior art procedures. A clear solution was maintainedthroughout the phosgenation. On completion of the phosgenation the masswas heated to 100 12 C. and salted with common salt until the Baum of a.filtered sample was 22. The salted mass was cooled with agitation,filtered when cold, and dried and standardized. The resultant powder wasused to dye paper and cotton a greenish-yellow with a high degree oflightfastness.

Examples 715.- Using the procedures described in the above examples,additional dyes were prepared from the intermediates shown in the tableprovided below. The dyes were recovered either as dry powders or assolutions and/ or suspensions and were employed in standard dyeingprecedures to dye paper. Examples 13-15 demonstrate the formation oftetraazo ureas using double coupling reactions as described above. AminoI-acid is 2-aminonaph thalene-5,7disu-lfonic acid; C-acid is2-aminonaphthalene- 4,8-disulfonic acid; and 1,6-Cleves acid isl-aminonaphthalene-6-sulfonic acid. GY is greenish-yellow; RY isreddish-yellow; YO is yellow-orange; YB is yellow-brown; and RB isreddish-brown.

Shade of tissue dyeing RY do Y do Cresidine Y 13 Amino G-aeid-- }1.Cresidine YB 2. m-Toluidine--.. 14 -.do ..}1. m-Toluidine YB 1 min G d2. Cresidine 0 am 15 "i2. 1,6-O1eves aeid Amnne RB The embodiments ofthe invention in which an exclusive property or privilege is claimed aredefined as follows:

1. The reaction mixture resulting from the improved process of forming astable, pumpable, concentrated aqueous solution or suspension of adirect disazo or tetraazo dye which has been prepared by phosgenating inan aqueous medium at a pH of 4.0-7.0 the alkali metal salt of a su1f0-or carboxy-arylazoaryl or arylazoarylazoaryl amine wherein terminal arylis phenyl or naphthyl and internal aryl is phenylene or naphthylene, theimprovement which consists of forming the solution or suspension of dyewhile simultaneously carrying out the phosgenation reaction bycontrolling the pH of the reaction medium with lithium hydroxide,lithium bicarbonate, lithium carbonate or ammonium hydroxide, thereaction mixture containing to 40 weight percent dye.

2. A stable, aqueous dye composition consisting of, on a weight basis,

10 10-25%, as the free acid, of the dye as hereinafter defined 0.751.5%Li+ 2-5 Cland SO 03% Na+ and K+ 0-8% dispersing agent balance, to makewater, said dye having the formula wherein:

A is phenyl or phenylene substituted by 1 to 2 CO M or SO M substituentsand by 0 to 2 OH, OCH or --CI-I substituents, or naphthyl or naphthylenesubstituted by 1 to 2 CO M or --SO M substituents and by 0 to 3 OH, OCHor CH substituents and M is selected from Li+, Na K and NHJ, with atleast 50 atom percent being selected from Li+ and NH B is phenylenesubstituted with 0 to 2 OH, OCH;,

or CH substituents; and

xis 1 to 2,yis0to Landthesumofxandyis 1to2.

3. In an improved process for dyeing paper by the cold water beatertechnique with direct disazo and tetraazo urea dyes, the improvementwhich comprises using the dye composition of claim 2.

References Cited UNITED STATES PATENTS 2,633,462 3/1953 Kehrer et a126017"5 X 2,777,840 1/1957 Wilhelm et a l 260- 3,621,008 11/1971 Ross eta1 260-175 GEORGE F. LESMES, Primary Examiner T. J. HERBERT, JR.,Assistant Examiner US. Cl. X.R.

Disclaimer 3,684,425.J07m M. Ross, WVilmington, De1., and H away I. Slim7061", C-arneys Point, NJ. PROCESS FOR DYEING PAPER WITH DISAZODYESTUFFS AND COMPOSITIONS THEREFOR. Patent dated Aug. 15, 1972.Disclaimer filed Feb. 26, 1975, by the assignee, E. I. du Pont de Nemom's and Company.

Hereby enters this disclaimer to claim 3 of said patent. '1:

[Ofiicial Gazette May 15, 1975.]

